Comparing COVID-19 vaccine effectiveness in Türkiye: heterologous, inactivated, and mRNA vaccines

Alpay Ari; Zeynep Altinay; Didem Demircan

doi:10.3855/jidc.21743

Comparing COVID-19 vaccine effectiveness in Türkiye: heterologous, inactivated, and mRNA vaccines

Authors

Alpay Ari Izmir Provincial Directorate of Health, University of Health Sciences Izmir Bozyaka Education and Research Hospital, Izmir, Türkiye
Zeynep Altinay University of Nevada-Reno, Reno, NV, United States
Didem Demircan Izmir Provincial Directorate of Health, University of Health Sciences Izmir Bozyaka Education and Research Hospital, Izmir, Türkiye https://orcid.org/0009-0002-3356-3187

DOI:

https://doi.org/10.3855/jidc.21743

Keywords:

protective effectiveness, public health, severe disease outcomes, vaccine strategy, COVID-19, pandemic

Abstract

Introduction: This study investigates the effectiveness of different coronavirus disease (COVID-19) vaccines in preventing hospitalization, ICU admissions, and mortality in Türkiye, upon comparing the responses to heterologous, inactivated, and mRNA vaccines.

Methodology: Data were gathered from 24,538 individuals, aged ≥ 18 years, whose COVID-19 status was confirmed through PCR testing. An analysis of the survival distributions for six vaccine types showed significant differences in severe disease outcomes, with distinct patterns observed for individuals older and younger than 65 years.

Results: Vaccines, including two-dose mRNA, both heterologous and homologous, showed the most protective and durable vaccine effectiveness. Homologous and heterologous inactivated vaccines demonstrated statistically significant reductions in severe COVID-19 outcomes for individuals aged > 65 years compared to unvaccinated individuals.

Conclusions: The results suggest that an early deployment of inactivated vaccines, despite being less advanced, may have played an important role in providing timely protection, mitigating severe outcomes, especially in countries with limited access to novel vaccine technologies. This study provides key insights for shaping future vaccine strategies and public health policies, particularly in regions with varying access to healthcare resources.

Author Biographies

Alpay Ari, Izmir Provincial Directorate of Health, University of Health Sciences Izmir Bozyaka Education and Research Hospital, Izmir, Türkiye

Associate Professor of Infectious Disease and Clinical Microbiology

Zeynep Altinay, University of Nevada-Reno, Reno, NV, United States

Zeynep Altinay, PhD, is an assistant professor of data visualization at the Reynolds School of Journalism at the University of Nevada, Reno. She studies public health and health communicaiton.

Didem Demircan, Izmir Provincial Directorate of Health, University of Health Sciences Izmir Bozyaka Education and Research Hospital, Izmir, Türkiye

Clinical Nurse Specialist

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Published

2026-05-31

How to Cite

Ari A, Altinay Z, Demircan D (2026) Comparing COVID-19 vaccine effectiveness in Türkiye: heterologous, inactivated, and mRNA vaccines. J Infect Dev Ctries 20:637–648. doi: 10.3855/jidc.21743

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Issue

Vol. 20 No. 05: May 2026

Section

Coronavirus Pandemic

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